Sean Manaea trade

We know that we could use a LH starter that's good for 160+ innings and has a slightly higher than average ground ball %. So can a lot of other teams. What is this 30yo one year rental worth and what would it take for the Cardinals to get him? His arbitration salary for 2022 should be @$10.3M. If he is a 3 WAR player, he'd provide an excess value of ~$15-20M. Plus, he'd probably be worth a qualifying offer (assuming that still exists) then too. But that is just the numbers piece. From a 'can this team go far in the playoffs?' perspective, Manaea also adds real value to this team.

So what's fair and what would it take? I don't know as much as you guys on prospect valuation. The best article I can find is the fangraphs blog from 2018. Throw in some inflation and a 45 POS player might do it? Looking at the Cards prospect list and who would be expendable - I'd say Malcolm Nunez fits the bill. Thoughts?